The present invention relates generally to externally mounted accessory antennas for vehicles. In particular, the invention relates to foldable antennas which are magnetically mountable on vehicles. Such vehicles include but are not limited to cars, trucks, farm machinery, boats or any of a number of other specialized vehicles that often do not include a communication antenna as original equipment.
Often persons find it desirable or advantageous to add communication equipment, such as a citizen's band radio, to their vehicle. Auxiliary antennas for such radios must correspondingly have the ability to be mounted upon a wide variety of vehicles. Manufacturers have found that antennas having a magnetic base are suitable for use on most vehicles because almost every vehicle includes at least one ferromagnetic surface. In other words, most vehicles include steel sheet metal somewhere on their exterior construction which is suitable to receive an antenna thereon. Such auxiliary antennas typically consist of a magnetic base unit, an antenna mounted upon the base unit and a coaxial cable connection between the antenna and the item of radio equipment in the vehicle. The magnetic base unit gives the buyer needed flexibility in deciding where on their vehicle they wish to mount the antenna. This flexibility is especially important to those persons having specialized vehicles, such as farmers, that often have limited space available for antennas.
One problem that has persisted with the use of auxiliary antennas of this type is that the strength of the attachment to the vehicle is only as strong as the magnet in the base unit. What this means in practice is that the antenna assemblies can be easily removed when desired but, unfortunately, they also have the potential of being dislodged from their original mounting location due to some disturbing force acting on the antenna. In other words, because the antenna normally extends above the vehicle, the antenna can strike an obstruction when the vehicle is driven into a shelter. The problem of the antenna becoming dislodged is especially critical when the antenna has the possibility of falling into machinery carried by the vehicle, often resulting in a destroyed antenna and damaged machinery. One example of this could be an antenna mounted upon a tractor. If the farmer forgets to remove the antenna each time he drives into his barn, he runs the risk that the antenna could be dislodged and fall into some undesirable location on or near the tractor resulting in a destroyed antenna and damaged farm machinery.
What is needed is an auxiliary antenna assembly that retains the flexibility provided by a magnetic base unit but which is not subject to becoming dislodged from the vehicle when the antenna strikes an obstruction. In particular, what is needed is an antenna which tends to remain upright but which is capable of yielding to an obstruction without dislodging the base unit from its intended mounting location.